Simplify the following expression: $y = \dfrac{x^2 - 11x + 18}{x - 9} $
Solution: First factor the polynomial in the numerator. $ x^2 - 11x + 18 = (x - 9)(x - 2) $ So we can rewrite the expression as: $y = \dfrac{(x - 9)(x - 2)}{x - 9} $ We can divide the numerator and denominator by $(x - 9)$ on condition that $x \neq 9$ Therefore $y = x - 2; x \neq 9$